Filtering devices, for instance rotary disc filter devices, are used especially for filtering off particles from liquids.
A common rotary disc filter is disclosed, for instance, in SE-C-224 131 and the principle thereof is illustrated in FIG. 1. The rotary disc filter 1 comprises a rotor having a horizontal, slowly rotating drum 11, which supports a number of parallel, disc-shaped filter members 12 which are successively arranged in spaced-apart relationship along the center axis of the drum 11 and which extend radially away from the drum (just partly shown in FIG. 1). The disc-shaped filter members 12 have, on their parallel orientated opposite lateral surfaces, openings which are covered with a filter cloth 13. Each rotary disc filter member 12 has a central opening through which a liquid A which is to be filtered can flow to the interior of the disc-shaped filter member 12. The liquid A is conducted through an inlet into the drum 11 and falls then down through openings in the drum into the interior of the disc-shaped filter elements 12, from which liquid A continues to flow out through the filter cloth 13 so that the particles which are to be filtered off adhere at the inside of the filter cloth 13.
U.S. Pat. No. 7,972,508 B2 discloses a rotary disc filter including a plurality of disc-shaped filter members secured about a drum. Each disc-shaped filter member has parallel orientated opposite lateral surfaces. The disc-shaped filter member is made of a plurality of modular frame members secured on the drum. The modular frame members may be made of plastic.
PCT/SE2007/000606 discloses a filter element for covering an opening in a disc-shaped filter member. The filter element is made of a filter cloth frame manufactured in one piece of cast light metal and a filter cloth which is glued to the filter cloth frame. The filter cloth frame may be made of a die-cast aluminum alloy.
The construction of the rotor of the rotary disc filter devices according to the prior art is complicated or requires the expensive manufacture of specific parts, like modules. Furthermore, the rotors according to the prior art are relatively heavy in weight. In order to support such a rotor it is necessary to provide a supporting structure having a high stability. Such supporting structure is expensive to manufacture. Furthermore, the rotor disc filter devices according to the prior art have a voluminous design.
It is desirable to reduce the cost of manufacture of a rotary disc filter device. Furthermore, it is desirable to reduce the volume of a rotary disc filter device.